Transmission-measuring apparatus



March 1929- I K. KUPFMULLER ET AL 1,705,926

TRANSMJISSION MEASURING APPARATUS Filed Aug. 25 1927 Patented Mar. 19, 1929.

" UNITED STATES PATENT OFFICE.

mm. xtirrmunnnn, or scnonnnnm-nnammnnn nuns MAYER m mn'rwn'r nuisance, or CHARLOTTENBURG-BERLIN, GERMANY, nssrenons 'ro smunns & HALSKE AKTIENGESELLSCHAFT, OF

A GERMAN COMPANY.

BIEMENSSTADT NEAR BERLIN, GERMANY.

TRAN SMISSION-MEA SUBIN G APPARATUS.

Applicationflled Au ust 25,1927, Serial No.

This invention relates in general to a method and arrangement for automatically measuring alternating potentials and is applicable chiefly to measuring the attenuation of long distance cable connections.

The increased reliability required of long toll cable connections has made supervisory devices and checking measurements necessary. Among these the so-called poling tests assume an important place. In prmclplea poling test is made by applying a certain energy L to the commencement of a long distance connection v( normally 1 milhwatt to a line of impedance Z =600) and measuring at the repeater exchanges of the lme, that portion L of the impressed energy arrlving thereat. From the ratio of the two performances L and L the attenuat1on factor b may be defined as 1/2 log 6 L/L In practice a poling test is carried out by applying to the end of the hue a generator with an internal impedance Z and an open circuit voltagevof E whereupon the voltage E occurring at the repeater exchange 1s measured. As normally the line shows the 1mpedance 'Z=600 .at the repeater exchange also, the attenuation or poling factor b is given by the ratio E b log) the indicated measuring device to the line" and to the auxiliary transmitter, and On the other hand by the regulating of the two voltages to equality. As pol-ing tests must be repeated very often during the operation and must be made simultaneous at all repeater exchanges of a long distance connection, it appears desirable to use an automatically 1ndicating measuring devlce for thlSPllIpOSB.

Such an automatic measurlnlg device forms the subject of the invention. I h s will be ex- "plained more closely in con unct1on with the basic circuit arrangement of ,WhlOh Flg. 1

215,428, and in Germany September 21, 1926.

shows the general layout and Figs. 2 and 3 curves explaining the operation of this layout. In Fig. 1 FL re resents a trunk line at the remote end of which a generator operates so that at a high resistance potentiometer S there is produced an alternatin potential E of the frequency w, which is to e measured. HG represents an auxiliary generator which is either self-energized or can be regulated from the line FL. This generator is first of all so set, for example, that it provides a constant voltage V,. The voltage V is preferably so measured that it corresponds tothe smallest voltage E arriving at S,.

The device contains further a rectifier G, a switch U, a pole changer PW, a condenser C, a relay R and a motor M. By means of a motor, the relayor a step ing mechanism,not shown, the switch U is t lIOWIl over at small intervals of time, say 50 per second so that first the voltage V taken from the potentiometer S and then the known voltage V is appliedto the input of the rectifying ar- The half waves arriving 'at the output of the rectifier are impressed on condenser C. The pole changer PW is so coupled to the switch U that the output and input of the rectifier arrangement is commutated simultaneously. The current charging the condenser then has a curve as shown in Fi 3 that is, condenser Cis positivel charged uring the time T while during t e time T it is negatively charged. If the two potentials V and V, are exactly equal the mean charge of the condenser is equal to 0, that is, the current flowing through the relay contains no direct current components so that, if it is sufficiently inert. it remains at rest. In order that the alternating components contained in the wave train according to Fig. 3, may be kept off the condenser C and the relay R the filter K mav be provided.

have different values.

For. thecase where the two voltages V and V are not equally great, the charging of the contact S are suitably chosen to .be a multiple of the intervals T and T,,. This is accomplished in a simple manner by the contact S being controlled through mechanism, not shown, from the switch Up The moving arm A of the potentiometer S, is coupled to the motor M through suitable mechanism, not shown. The motor shifts this arm until the voltage V tapped from it has become exactly equal to the fixed auxiliary voltage V At this instant the relay becomes dead and cuts out the motor M. The potentiometer S,, which is suitably calibrated in attenuation units, indicates the de sired ratio.

What is claimed is:

1. An electrical measuring circuit comprising a source of voltage to be measured, an auxiliary source of voltage, means for rectifying said voltages, means for impressing said voltages alternately upon said rectifying means, and means controlled by the output of said rectifying means for equalizing said volta es.

2. An e ectrical measuring circuit in accordance with claim 1 in which said means controlled by the output of said rectifying means comprises a condenser alternately charged from said rectifying means, and a relay operated by the difference in the values of said voltages on said condenser.

3. An electrical measuring circuit in accor-dance with claim 1 in which said means controlled by the output of said rectifying means comprises a condenser, a relay, and a motor, said motor being controlled by said relay and operated to maintain said first voltage (2x131 to said auxiliary voltage.

4. electrical measuring circuit com.-

e controlled to rotate either right or left. The make and break intervals polarity, said polarity being reversed in synages on said rectifier, a motor, and a relay for controlling said motor, said relay being operated by the difference in the values of said voltages, said motor operating mechanism to maintain said voltages equal.

chronism with the impression of said volt- 5. A method of automatically measuring the changes in a voltage in which said voltage is compared with an auxiliary source of constant voltage, comprising first, rectifying each'of said voltages alternately, second, impressing the output ofeachof said voltages upon a condenser in alternate reverse polarity and in synchronism with the alternate rectification of said voltages, the difference in said output controlling the adjustment of said voltages to equality.

6. A method of automatically measuring a voltage by comparison with an auxiliary standard voltage comprising, first, alternately rectifying said voltages, second, alternately charging a condenser with said voltages m alternate opposite polarity, and third, impressing the difference in the charges of said condenser on mechanism for adjusting said voltages to equality.

7. In an electrical measuring circuit, va voltage to be measured, an auxiliary voltage of constant value, a rectifier, switching means for alternately impressing said voltages on said rectifier, a condenser, a second switch-' ing means for alternately impressing the rectified-voltages on said condenser in reverse polarity in synchronism with the impression of said voltages on said rectifier, a filter intermediate said condenser and said second switching means for suppressing alternating components in the output of said rectifier, a relay operable by the charge on said condoms er, and motor means controlled by said re lay for adjusting the value of said voltage to equal that of said auxiliary voltage.

In witness whereof, We hereunto subscribe our names this 3rd day of August, A. D. 1927.

KARL 'KUPFMULLER. I HANS MAYER. DIETWALT THIERBACH. 

